On 7/31/2026 2:43 PM, Patrick McNeil via tz wrote:
As an Albertan, seeing |date| or system logs print |CST| after November 1 will immediately be interpreted as a system error or wrong time zone configuration by almost all residents and local administrators. In the same way you would not expect an Angeleno to identify as being on Mountain Time when opting out of DST, Albertans universally consider themselves on Mountain Time (MDT/MST), not Central Time. A numerical offset of "-06" would be preferable to "CST".
The challenge will come from where Alberta residents are getting their time. For example, Windows users cannot yet choose a time zone for "(UTC-06:00) Alberta" or "(UTC-07:00) British Columbia". I suspect that most Alberta residents have their Windows time set to "(UTC-07:00) Mountain Time (US & Canada)". Once Windows updates their software, many residents will need to adjust their zone lest they "fall back" with Los Angeles and Denver. Based on web searches, Apple products such as the iPhone are ready but some glitches have been reported. Google users are reporting issues with dates past November 1st. These major players should have everything sorted out by November 1st but trying to coordinate a meeting across a time zone division may not be reliable until November.
BTW: As a test I set my Android phone to Region: Canada and Time Zone: Edmonton and it reports Mountain Standard Time begins November 1, 2026. If I select Region: Canada and Time Zone: Vancouver it reports "Uses Pacific Time (GMT-07:00). No daylight savings time."
As for system administrators, I am assuming that the system in question is tzdata aware and is set to America/Edmonton. Assuming it is running on tzdata 2026c (released July 8th) you will see MDT change to CST on November 1st. When you say "interpreted as a system error or wrong time zone configuration" are you referring to human interpretation? Administrators asking why their system is showing CST (as if it were configured for Saskatchewan) instead of MDT or MST? Or do you have some sort of automated log reader that will be confused by the change in name? I suspect that some administrators would find confusion if their logs started showing -06 instead of MST/MDT.
Now would be a good time for system administrators to go through their systems and make sure systems are set on the best available time zone. If you run Windows servers keep an eye out for the system update that will allow you to choose "(UTC-06) Alberta, Saskatchewan" (or however Microsoft chooses to solve the issue).
Best wishes on working through the change. While Albertans will not "feel the pain of changing their clocks" this fall they may not realize how many people are working behind the scenes to make that work as seamless as possible.
